Dynamic Resource Style in WPF

Hi All,
In my WPF application I Wrote some styles for button in App.xaml and in my Window.xaml I mentioned Style="{DynamicResource MyStyle1}" for a button but that style is not getting reflected when i run the application. Let me know how do i get those styles..
This is the code i placed in App.xaml
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
StartupUri="Page2.xaml">

and the following is the code in window. xaml
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window2" Height="300" Width="300">